Halogen-Free Ionic Liquid for Heat-Resistant Green Solvent Applications
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Solution Overview
Problem
Existing ionic liquids often contain halogen atoms, leading to environmental concerns and high production costs, and lack both good heat resistance and hydrophobic properties, which are necessary for effective separation from water.
Innovation Solution
A halogen-free ionic liquid composed of an asymmetric tetraalkylphosphonium cation with long alkyl chains and a trialkylsilyl group-containing alkylsulfonic acid anion, which exhibits excellent heat stability and hydrophobic properties, allowing for easy separation from water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ionic liquids contain fluorine atoms to improve heat resistance, then heat stability is improved, but environmental impact increases and production cost increases
Solution Approach 1:
The invention changes the chemical composition parameters by replacing fluorinated anions with non-fluorinated carboxylate anions while adjusting the cation structure (using tetraalkylphosphonium with specific alkyl chain lengths) to achieve the desired heat stability without fluorine atoms. This parameter substitution resolves the contradiction between heat stability and environmental impact.
2Stability of the object's composition
If ionic liquids are made hydrophobic by adding fluorine atoms, then phase separation with water is improved, but environmental impact increases
Solution Approach 1:
The invention changes the chemical composition by using non-fluorinated carboxylate anions combined with tetraalkylphosphonium cations having appropriate alkyl chain lengths (where the alkyl groups contain 4-20 carbon atoms). This compositional parameter change achieves hydrophobicity and phase separation without relying on fluorine atoms, thereby reducing environmental impact.
3Object-affected harmful factors
If ionic liquids use non-fluorinated anions to reduce environmental impact, then environmental friendliness is improved, but heat resistance decreases and viscosity increases
Solution Approach 1:
The invention creates a composite ionic liquid system by combining tetraalkylphosphonium cations with specific alkyl chain compositions (4-20 carbon atoms) and non-fluorinated carboxylate anions. This composite structure achieves both environmental friendliness and adequate heat resistance by leveraging the synergistic effects of the cation-anion combination and alkyl chain characteristics.
4Ease of manufacture
If ionic liquids use simple structures to reduce production cost, then manufacturing cost is reduced, but heat resistance and hydrophobicity are insufficient
Solution Approach 1:
The invention optimizes structural parameters by specifying tetraalkylphosphonium cations with alkyl groups containing 4-20 carbon atoms and non-fluorinated carboxylate anions. This parameter optimization achieves the desired heat resistance and hydrophobicity while maintaining reasonable production costs by avoiding complex fluorinated structures and using readily available carboxylic acid components.
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AI summary
An ionic liquid characterized by comprising a phosphonium salt represented by formula (1), which has such characteristic properties that no halogen atom is contained, thermal stability is excellent and hydrophobicity is exerted. (In the formula, R1 represents an alkyl group having 1 to 10 carbon atoms; R2 represents an alkyl group having 8 to 20 carbon atoms; R3 represents an alkyl group having 1 to 8 carbon atoms; and n represents an integer of 1 to 12; wherein the number of carbon atoms in R2 is greater than that in R1.)